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Variability of cannabis plant gender - is a seed male or female from birth?

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    Variability of cannabis plant gender - is a seed male or female from birth?

    As we all know, only female cannabis plants make buds, and male plants not only make pollen sacs which can't be smoked, they can pollinate your female plants and give you seedy buds. Because of that, we try to identify males in the grow room and remove them immediately. This is also why many small-scale growers use feminized seeds - they know every seedling will end up being a female plant.

    Unfortunately with regular (non-feminized) seeds, only half of all seedlings end up being female, and the other half ends up being male.

    Or is that always true?

    A grower named ManOGreen recently shared an article by Jorge Cervantes that mentions the variability of plant gender when a seedling is first born. Jorge talks about how it's important to make sure a plant has actually expressed its gender before taking cannabis clones.

    Take clones from mother plants that are at least 2 months old. If taking clones from seedlings, wait until male or female pre-flowers are easily visible with the naked eye. Clones taken from female plants cloned before they have expressed sex may dawn male flowers or develop poorly when induced to flower with a 12/12-hour day/night photo-period.
    This reminds me of an outdoor grower I talked to a few years ago who swore you could get more than 50% females from regular seeds if you control the environment during the first month of growth. He said the following things would dramatically increase the percentage of female plants if done during the first 4 weeks up to the point where you could get 70% females.

    Ways to possibly increase percentage of female plants from regular seeds (more study is needed!)
    • Cool temperatures (65-75°F day and night)
    • High humidity (50-70% RH)
    • Short but not too short days. Keep consistent day and night periods with no light interruptions at night, and days should be 14-18 hours long (between 14/10 and 18/6)
    • Blue light. Always start seeds under a vegetative grow light (something with plenty of blue like a Metal Halide or a 6500k CFL/T5/fluorescent)
    • Make sure to provide plenty of Nitrogen - don't let plants get nutrient starved or run into deficiencies
    • Prevent stress, especially heat or light stress during first 4 weeks
    • Avoid over and especially under watering
    On the other hand, he said that a lot of environmental or light stress during the first few weeks, combined with hot, dry temperatures, could net him up to 70% male plants!

    From reading about other types of plants with dedicated male/females (dioecious plants), it seems like many species don't really have X and Y chromosomes, as much as sex-linked genetic markers that cause the plant to tend to be either "more" male or female on average. So if you breed two plants together that have already been determined to be female, the resulting seeds are nearly all female because it's getting lots of "female-ness" from both parents. But there are environmental factors that can "break" the natural tendency of a plant, which you theoretically could use with regular seeds to try to get more plants to grow buds.

    Another example of variable gender expression is the fact that you can use colloidal silver or gibberellic acid to force known female plants to produce pollen sacs in the flowering stage, and you can use ethephon on male/hemie plants to force buds. This also goes along with the fact that you can get a female plant to produce male flowers (turn hermie) under environmental factors like stress.

    Overall it seems like there's a lot of evidence supporting the idea that gender is at least somewhat variable with cannabis plants. So to me it makes sense there could be ways to help control a young seedling's gender expression.

    For growers out there who've grown out big batches of seeds, what has been your experience? What are your tips for increasing the percentage of female plants with regular marijuana seeds?


    I have a batch of regular/random freebies- seeds and attempted to sex the seeds by the seed shape and attachment point appearance.

    While I have no idea if there is any creedence to this hocus/pocus- It won't hurt to try by planting the identified Fems first- and then grow all of them following the recommendations listed above.

    I'm a very small personal grower and plan to begin this in a couple of months, but may take a year to complete- and retest.

    Certainly, all the conditions mentioned in your post to get Fem plants-are good growing practices anyways, for healthy plants and should be followed.
    It's all bullshit - until you smoke it!

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      I am as far from an expert as you can get. But it seems possible to me that stress during the first few weeks could indeed turn an otherwise female seed into a male. Since the plant isn't sexually mature yet, it is different from a hermie which exhibits signs of both sexes. The immature, possible female, seed(ling) will grow up to only develop the male parts. Thus more males than females from a batch of seeds.

      The other side of the coin - getting more females - I got nothin'.


        For grow 2016,I planted 10 cherry hash(regular seeds) outdoor grow) out of that four were male but six were female.,next I had six Ghost train haze they went 50/50 three male three female.Next was seven Grapefruit,four males three females.I only grow regular seeds,like to play the odds.(But that is me)I planted four LSD as well,I had a rabbit eat down all four seedlings,only had one live and this one had only one round leaf left,I figured this one would die as well,but after some extra love it started to grow,it was still the runt of all the plants but it still had a nice cola in the end.(I think ) that seeds have a predetermined sex,however certain environmental stress could cause a reversal.The worst ratio I had was with Indiana bubblegum,planted 10,got three female,this was 70/30 male-female.Some of the all female seeds I have grown,while they were all female,a few had some weird deformities,


          Here's an idea; keep banana peels near germinated seeds to increase ethylene concentrations.


            Smokey McPot:

            That might not be as crazy as it sounds:

            "The Cucurbitaceae crops are dioecious plants, and female flowers and male flowers are respectively formed on a genetically identical single plant by physiological factors. In the Cucurbitaceae crops, a case of inducing female flowers by ethylene treatment is known, and in cucumber it is suggested that the stamen development is inhibited by ethylene and an female flower is formed thereon (Non Patent Literature 6). Further, it is reported that a hermaphrodite flower is formed when a female plant of Momordica dioica plant belonging to the Cucurbitaceae, a dioecious plant, is treated with silver nitrate, which is an ethylene inhibitor (Non Patent Literature 7). "
            This invention relates to: a method for controlling the sexuality of hop, comprising applying a chemical to a hop female plant once or more and forming a fertile male flower capable of forming pollen on the female plant, wherein the chemical reduces a reaction with endogenous ethylene in the female plant; an embryo or seed, hop plant, and cone, capable of being obtained through the method; a method of screening for a hop plant; and a method of producing a hop plant variety.


              How would the ethelyne get absorbed by the plant? What is a treatment considered?


              • tree dawg
                tree dawg commented
                Editing a comment
                dutch passion seed company put out article on this very subject

              You can actually use ethephon on hemie plants to force buds, like the reverse of colloidal silver/giberellic acid for females. Ethephon is what's in products that are supposed to stop hermies like Optic Foliar Switch and Dutch Master Reverse. Ethephon works because it quickly turns into ethylene. It makes you wonder if something as simple as banana peels in the grow room could help fight hermies (if you can prevent them from attracting fruit fries and other bugs lol). You definitely want a more pure way to provide ethylene to your plants, though that might be why they use ethephon. Could a bunch of ethylene even make a full male plant produce buds? I have no idea but it I could see how that would be helpful for breeding. Or are you just asking for problems?


                You would think its the opposite process to things like colloidal silver, which inhibits the ethelyne absorption if I'm not mistaken.


                  The Organic gardener in me says NO to growth hormone regulators - but apples and bananas give off ethylene Soooooooooooo I duno?


                    dutch passion put out written about this I am interested I believe it to be true


                      I have tried keeping seeds in a container with banana peels (fresh peel every 2-3 days) keeping the peels wrapped in paper towels for moisture. Planted 10 seeds and had 8 females. Pretty good odds for bagseed


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